JP6859693B2 - Insulated wire - Google Patents

Description

The present invention relates to an insulated electric wire.

A coil wound with an insulated wire is used as a component of general household electrical equipment, automobile electrical equipment, and the like. The insulated wire constituting such a coil includes a conductive metal conductor and a resin insulating layer covering the conductor.

The insulating layer of such an insulated wire is required to have workability (flexibility) when winding the insulated wire. Insulated electric wires have been proposed in which the insulating layer contains specific inorganic fine particles in order to improve the insulating properties while maintaining the workability of the insulating layer of the insulated electric wire (Patent Document 1).

JP-A-2007-141507

As described above, the insulating layer of the insulated wire is required to have workability. In addition, the insulating layer of the insulated wire is also required to have scratch resistance. In order to improve the scratch resistance of the insulating layer, it is conceivable to increase the elastic modulus of the insulating layer and harden the insulating layer. However, when the elastic modulus of the insulating layer is increased, the insulating layer becomes brittle and the workability is lowered.

Therefore, one of the purposes is to provide an insulated wire having an insulating layer having both scratch resistance and workability.

The insulated wire of the present application includes a conductor portion having a linear shape and made of metal, and an insulating layer covering the outer peripheral surface of the conductor portion. The insulating layer includes a high-strength insulating layer. The high-strength insulating layer contains a matrix made of synthetic resin and cellulose nanofibers dispersed in the matrix. In the high-strength insulating layer, the content of the cellulose nanofibers is 0.1 part by mass to 10 parts by mass with respect to 100 parts by mass of the synthetic resin constituting the matrix.

According to the above-mentioned insulated wire, it is possible to provide an insulated wire having an insulating layer having both scratch resistance and workability.

It is sectional drawing which shows an example of an insulated electric wire. It is a schematic diagram which shows the structure of a high-strength insulating layer.

[Explanation of Embodiments of the Invention]
First, embodiments of the present invention will be listed and described. A conductor portion having a linear shape and made of metal, and an insulating layer covering the outer peripheral surface of the conductor portion are provided. The insulating layer includes a high-strength insulating layer. The high-strength insulating layer contains a matrix made of synthetic resin and cellulose nanofibers dispersed in the matrix. In the high-strength insulating layer, the content of the cellulose nanofibers is 0.1 part by mass to 10 parts by mass with respect to 100 parts by mass of the synthetic resin constituting the matrix.

In the insulated wire of the present application, the insulating layer includes a high-strength insulating layer, and cellulose nanofibers are dispersed in the matrix of the high-strength insulating layer. By doing so, damage to the insulating layer is suppressed and scratch resistance is improved. Further, by setting the content of the cellulose nanofibers to 10 parts by mass or less with respect to 100 parts by mass of the synthetic resin constituting the matrix, it is possible to suppress a decrease in workability of the insulating layer. On the other hand, when the content of the cellulose nanofibers is 0.1 parts by mass or more, the effect of improving the scratch resistance can be surely obtained. As a result, according to the insulated wire of the present application, it is possible to provide an insulated wire having an insulating layer having both scratch resistance and workability.

In the above-mentioned insulated wire, the cellulose nanofibers preferably have an average fiber diameter of 0.1 nm to 100 nm and an average fiber length of 0.1 μm or more. By doing so, the scratch resistance of the insulating layer can be improved more reliably.

In the above-mentioned insulated wire, the synthetic resin preferably contains polyimide. Synthetic resins containing polyimide are excellent in insulating properties and heat resistance. Therefore, polyimide is suitable as a material for forming an insulating layer.

[Details of Embodiments of the present invention]
Next, an embodiment of the insulated wire of the present application will be described with reference to the drawings. In the drawings below, the same or corresponding parts are given the same reference number and the explanation is not repeated.

(Structure of insulated wire)
An example of the insulated wire 1 in this embodiment is shown in FIG. FIG. 1 is a schematic cross-sectional view showing a cross section perpendicular to the longitudinal direction of the insulated wire 1. With reference to FIG. 1, the insulated wire 1 has a rectangular cross-sectional shape with rounded corners. The insulated wire 1 includes a linear conductor portion 10 having a rectangular cross-sectional shape with rounded corners, and an insulating layer 20 that covers the outer peripheral surface of the conductor portion 10.

(Conductor part)
In the present embodiment, the conductor portion 10 has a rectangular shape with rounded corners in a cross section perpendicular to the longitudinal direction. As the conductor portion 10, as in the present embodiment, in addition to a flat wire having a rectangular cross-sectional shape perpendicular to the longitudinal direction, a circular wire having a circular cross-sectional shape and a square wire having a square cross-sectional shape. , A stranded wire obtained by twisting a plurality of strands is used.

When a flat wire is used for the conductor portion 10, the insulated wire 1 may be wound in a coil shape so that the short side of the cross section perpendicular to the longitudinal direction of the insulated wire 1 forms the outer peripheral surface and the inner peripheral surface. In such a case, the insulating layer 20 of the insulated wire 1 is required to have further workability. According to the insulated wire 1 of the present embodiment, it is easy to impart sufficient workability even when a flat wire is used for the conductor portion 10.

The conductor portion 10 is made of metal. As the metal constituting the conductor portion 10, a metal having high conductivity and high mechanical strength is preferable. In the present embodiment, the conductor portion 10 is made of copper. As the conductor portion 10, in addition to the copper of the present embodiment, a copper alloy, aluminum, nickel, silver, iron, steel, stainless steel or the like can be used. As the conductor portion 10, one in which the above-mentioned metal is linearly formed or one in which the above-mentioned metal is linearly formed and another metal is coated can be used. Examples of the multi-layered conductor portion 10 include nickel-coated copper wire, silver-coated copper wire, copper-coated aluminum wire, and copper-coated steel wire.

(Insulation layer)
With reference to FIG. 1, the insulating layer 20 constituting the insulated wire 1 includes a high-strength insulating layer 201. The insulating layer 20 constituting the insulated wire 1 is composed of only the high-strength insulating layer 201 as in the present embodiment, and also has a structure in which a plurality of insulating layers are laminated, and at least one of them has high strength. It may be the insulating layer 201. The high-strength insulating layer 201 includes a matrix 21 made of a synthetic resin. Examples of the synthetic resin constituting the matrix 21 include a thermosetting resin and a thermoplastic resin. In the present embodiment, the synthetic resin constituting the matrix 21 contains polyimide. Since the synthetic resin containing polyimide is excellent in insulating property and heat resistance, it is suitable as a material for forming the high-strength insulating layer 201. The insulating layer 20 includes a matrix 21 made of a synthetic resin like the high-strength insulating layer 201.

In addition to the polyimide of the present embodiment, the synthetic resin constituting the matrix 21 includes polyamideimide, polyesterimide, polyetherimide, polyamide, polyurethane, polyester, polybenzoimidazole, melamine resin, polyvinylformal, epoxy resin, phenol resin, and the like. Thermosetting resins such as urea resin and acrylic resin can also be used. Examples of the synthetic resin constituting the matrix 21 include polyamide, polycarbonate, polybutylene terephthalate, polyethylene terephthalate, polybutylene naphthalate, polyethylene naphthalate, polysulfone, polyether sulphon, polyphenyl sulphon, polyetherimide, and polyphenylene sulfide. , Polyetherketone, polyaryletherketone, tetrafluoroethylene / ethylene copolymer, polyetheretherketone, polytetrafluoroethylene, thermoplastic polyimide resin, polyamideimide and other thermoplastic resins can also be used. The high-strength insulating layer 201 may be a composite or laminate of two or more types of resins, or may be a composite or laminate of a thermosetting resin and a thermoplastic resin.

The thickness of the insulating layer 20 is, for example, 5 μm or more and 200 μm or less. Within such a range, the conductor portion 10 can be sufficiently insulated.

FIG. 2 is a schematic view showing a high-strength insulating layer 201 constituting the insulating layer 20 of the present embodiment. With reference to FIG. 2, the high-strength insulating layer 201 contains cellulose nanofibers 22 dispersed in the matrix 21. The cellulose nanofiber 22 has high strength and high elastic modulus. As a result, damage to the insulating layer 20 is suppressed, and scratch resistance is improved.

(Cellulose nanofiber)
The cellulose nanofiber 22 in the present embodiment is a cellulose nanofiber 22 obtained from a plant-derived cellulose fiber. Cellulose nanofibers 22 obtained from plant-derived cellulose fibers are suitable as materials for forming the high-strength insulating layer 201 because they are highly productive and have an appropriate fiber diameter and fiber length.

The cellulose nanofiber 22 is not particularly limited as long as it is formed of a polysaccharide having a β-1,4-glucan structure. The cellulose nanofiber 22 may be a cellulose nanofiber 22 obtained from the plant-derived cellulose fiber of the present embodiment, an animal-derived cellulose fiber, a bacterial-derived cellulose fiber, or the like. .. Plant-derived cellulose fibers include wood fibers (wood pulp such as conifers and broadleaf trees), bamboo fibers, sugar cane fibers, seed hair fibers (cotton linters, bombax cotton, capoc, etc.), and gin skin fibers (eg, hemp, hemp, etc.). Kozo, Mitsumata, etc.), leaf fiber (for example, Manila hemp, New Zealand hemp, etc.) and the like can be used. Of these, pulp-derived cellulose fibers such as wood fibers and seed hair fibers are preferable. These cellulose nanofibers 22 can be used alone or in combination of two or more.

The cellulose nanofiber 22 in the present embodiment has an average fiber diameter of 0.1 nm to 100 nm and an average fiber length of 0.1 μm or more. By doing so, the scratch resistance of the insulating layer 20 can be improved more reliably. The average fiber length of the cellulose nanofibers 22 is preferably 0.1 μm to 100 μm from the viewpoint of dispersibility. The average fiber diameter and the average fiber length are values calculated from the fiber diameter (n = about 10) and the fiber length (n = about 10) measured based on the electron microscope image.

The content of the cellulose nanofibers 22 in the present embodiment is 0.1 parts by mass to 10 parts by mass with respect to 100 parts by weight of the synthetic resin constituting the matrix 21. Since the cellulose nanofibers 22 have high strength, it is possible to improve the scratch resistance while suppressing the deterioration of the processability of the insulating layer 20 by setting such a content. The preferable range of the content of the cellulose nanofibers 22 is 1 part by mass to 6 parts by mass with respect to 100 parts by weight of the synthetic resin constituting the matrix 21.

The cellulose nanofibers 22 may be surface-modified from the viewpoint of dispersibility. More specifically, it may be a modified cellulose nanofiber obtained by further adding a compound that modifies the cellulose nanofiber 22 and reacting it with the cellulose nanofiber 22.

Here, in the insulated wire 1 of the present embodiment, the insulating layer 20 includes the high-strength insulating layer 201, and the cellulose nanofibers 22 are dispersed in the matrix 21 of the high-strength insulating layer 201. By doing so, damage to the insulating layer 20 is suppressed, and scratch resistance is improved. Further, by setting the content of the cellulose nanofibers 22 to 10 parts by mass or less with respect to 100 parts by mass of the synthetic resin constituting the matrix 21, deterioration of the workability of the insulating layer 20 can be suppressed. On the other hand, by setting the content of the cellulose nanofibers 22 to 0.1 parts by mass or more, the effect of improving the scratch resistance can be surely obtained. As a result, it is possible to provide the insulated wire 1 provided with the insulating layer 20 having both scratch resistance and workability.

(Manufacturing method of insulated wire)
Next, the outline of the manufacturing method of the insulated wire 1 will be described. The method for manufacturing the insulated wire 1 includes a step of preparing the conductor portion 10, a step of applying a resin composition to be an insulating layer 20 on the outer peripheral surface of the conductor portion 10, and a step of curing the applied resin composition by heating. It has a process.

In the step of preparing the conductor portion 10, the conductor portion 10 which is a wire rod made of a conductor such as copper is prepared. In the step of applying the resin composition, the resin composition to be the insulating layer 20 is applied to the outer peripheral surface side of the conductor portion 10. As the synthetic resin constituting the resin composition, for example, polyimide which is a thermosetting resin can be adopted. As a method of applying the resin composition to the outer peripheral surface side of the conductor portion 10, a method using a coating device including a liquid composition tank for storing the liquid resin composition and a coating die can be mentioned. According to this coating device, the resin composition adheres to the outer peripheral surface side of the conductor when the conductor portion 10 passes through the liquid composition tank, and then passes through the coating die to make the resin composition uniform in thickness. It is applied.

In the step of curing the resin composition, the resin composition is cured by heating to form the insulating layer 20. As an apparatus used for this heating, a tubular baking furnace extending along the traveling direction of the conductor portion 10 coated with the resin composition can be used. As the heating method, hot air heating, infrared heating, high frequency heating and the like can be adopted. The heating temperature is, for example, 300 ° C. or higher and 600 ° C. or lower.

The resin composition coating step and the resin composition curing step may be repeated a plurality of times. By doing so, the thickness of the insulating layer 20 can be increased. By the above procedure, the insulated wire 1 of the present embodiment can be manufactured.

Similar to the insulated wire 1 of the present embodiment, a sample provided with the insulating layer 20 composed of only the high-strength insulating layer 201 in which the cellulose nanofibers 22 are dispersed in the matrix 21 is prepared, and the tensile elastic modulus of the insulating layer 20 and the tensile elastic modulus Evaluation was performed to confirm the breaking elongation and the insulating breakdown voltage of the insulated wire 1. The evaluation procedure is as follows.

A copper wire having a diameter of 1 mm was prepared. Further, a varnish containing polyimide was prepared, and a resin composition in which cellulose nanofibers 22 were mixed was prepared. Further, for comparison, a resin composition containing no cellulose nanofibers 22 and a resin composition in which silica was mixed instead of the cellulose nanofibers 22 were prepared. The resin composition was applied to the above copper wire, and the resin composition was cured by heating to form an insulating layer 20 composed of only the high-strength insulating layer 201. The thickness of the insulating layer 20 is 32 μm. Sample No. containing cellulose nanofibers 22 in the proportion shown in Table 1. 1-No. Sample No. 8 containing silica in the proportion shown in Table 1. 9 and was produced. Prepared sample No. 1-No. Regarding No. 9, the tensile elastic modulus and breaking elongation of the insulating layer 20 and the dielectric breakdown voltage of the insulated wire 1 were evaluated by the following methods. The results are shown in Table 1.

The tensile modulus was evaluated according to JIS C3005: 2014. More specifically, after removing the conductor portion 10 to prepare a tubular test piece having only the insulating layer 20, both ends of the test piece are attached to the chuck of a tensile tester in an environment of 23 ° C., and then the tensile speed. It was pulled at 200 mm / min, and the inclination of the SS curve was taken as the tensile elastic modulus.

The elongation at break was measured according to JIS C3005: 2014. More specifically, after removing the conductor portion 10 to prepare a tubular test piece having only the insulating layer 20, both ends of the test piece are attached to the chuck of the tensile tester in an environment of 23 ° C., and then the tensile speed. The test piece was pulled at 200 mm / min and the elongation at break of the test piece was measured.

The dielectric breakdown voltage was measured with a test piece prepared by the method from two pieces in accordance with JIS C3003: 1999. More specifically, 10 test pieces having a length of about 50 cm are taken, each of them is folded in two, and the portion having a length of about 12 cm is twisted 9 times while applying a tension of 15 N. After removing the tension, cut the crease and make a test piece from two pieces. From these two, an AC voltage having a waveform close to a sine wave of 50 Hz or 60 Hz is applied between the two conductors of the test piece while boosting at 500 V / s, and the voltage when the insulating film is destroyed and a short circuit occurs. (KV) was measured for 10 test pieces and the average value was calculated.

表１を参照して、セルロースナノファイバー２２を含まないＮｏ．６、およびセルロースナノファイバー２２を０．０５質量部含むＮｏ．７と比較して、セルロースナノファイバー２２を０．１質量部以上含むＮｏ．１〜Ｎｏ．５、Ｎｏ．８では、引張弾性率が明確に上昇している。このため、セルロースナノファイバー２２の含有量は、耐傷性の点から０．１質量部以上とすることが好ましいといえる。また、セルロースナノファイバー２２を１０質量部よりも多く含むＮｏ．８では、セルロースナノファイバー２２を含まないＮｏ．６と比較して破断伸びが著しく低下している。このため、セルロースナノファイバー２２の含有量は、加工性の点から１０質量部以下とすることが好ましいといえる。また、シリカを含むＮｏ．９と比較して、セルロースナノファイバー２２を含むＮｏ．１〜Ｎｏ．５では、破断伸びおよび絶縁破壊電圧の低下が抑制されている。

With reference to Table 1, No. 1 containing no cellulose nanofiber 22. No. 6 and 0.05 parts by mass of cellulose nanofibers 22. No. 7 containing 0.1 part by mass or more of cellulose nanofibers 22 as compared with 7. 1-No. 5, No. In No. 8, the tensile elastic modulus is clearly increased. Therefore, it can be said that the content of the cellulose nanofibers 22 is preferably 0.1 part by mass or more from the viewpoint of scratch resistance. In addition, No. 1 containing more than 10 parts by mass of cellulose nanofibers 22. In No. 8, No. 8 does not contain cellulose nanofibers 22. Compared with No. 6, the elongation at break is significantly reduced. Therefore, it can be said that the content of the cellulose nanofibers 22 is preferably 10 parts by mass or less from the viewpoint of processability. In addition, No. 1 containing silica. No. 9 containing cellulose nanofibers 22 as compared to 9. 1-No. In No. 5, the elongation at break and the decrease in the breakdown voltage are suppressed.

It should be understood that the embodiments and examples disclosed here are exemplary in all respects and are not restrictive in any way. The scope of the present invention is not defined as described above, but is indicated by the scope of claims, and is intended to include all modifications within the meaning and scope equivalent to the scope of claims.

The insulated wire of the present application is particularly advantageously applied to an insulated wire that is required to have an insulating layer having both scratch resistance and workability.

1 Insulated electric wire 10 Conductor 20 Insulated layer 201 High-strength insulating layer 21 Matrix 22 Cellulose nanofibers

Claims (3)

A conductor part that has a linear shape and is made of metal,
An insulating layer that covers the outer peripheral surface of the conductor portion and
With
The insulating layer includes a high-strength insulating layer having a thickness of 5 μm or more and 200 μm or less.
The high-strength insulating layer is
A matrix made of synthetic resin containing polyimide and
Containing cellulose nanofibers dispersed in the matrix
In the high-strength insulating layer, the content of the cellulose nanofibers is 0.1 part by mass to 10 parts by mass with respect to 100 parts by mass of the synthetic resin constituting the matrix. The insulated wire according to claim 1, wherein the cellulose nanofibers have an average fiber diameter of 0.1 nm to 100 nm and an average fiber length of 0.1 μm or more. The insulated wire according to claim 1 or 2, wherein the synthetic resin is polyimide.

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